RU2565711C1 - Method to manufacture honeycomb filler - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method includes application of glue strips onto cloth of glass cloth in longitudinal direction, cutting of glass cloth into stocks in direction perpendicular to glue strips, assembly of a honeycomb package by laying each stock with a shift relative to the previous one by half-pitch of glue strips, gluing of honeycomb package stocks according to the specified mode, thermal stabilisation of the freely suspended honeycomb package, production of the honeycomb block with the specified face of the cell by stretching of the honeycomb package, impregnation of the honeycomb block by a polymer binder with subsequent thermal hardening, afterwards the honeycomb block is cut into honeycomb panels of specified height, in the produced honeycomb panels along their entire area they carry out even removal of faces of three adjacent cells in contact with each other at height of the honeycomb panel, besides, the value of the removed part of the cell faces makes 0.25-0.33 of face length.

EFFECT: invention makes it possible to manufacture a honeycomb filler for items of complex curvature.

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Description

The invention relates to a method for manufacturing honeycomb core from fiberglass and can be used in rocket, aircraft and shipbuilding, construction, furniture and packaging industries in the manufacture of three-layer structures of complex curvature.

A known method of manufacturing a honeycomb core based on fiberglass fabrics, which includes the following operations: applying adhesive strips to the fiberglass in the longitudinal direction and cutting it into blanks in a direction perpendicular to the adhesive stripes, assembling a package of blanks with each layer offset by half a step of adhesive strips, gluing blanks of the honeycomb bag under pressure with heating and obtaining a honeycomb block by stretching the honeycomb bag, impregnating it with a polymer binder and thermosetting, cutting the resulting cell block on a flat panel [V.E. Bersudsky, V.N. Krysin, S.I. Forest. Manufacturing technology of cellular aviation structures. M .: Engineering, 1975, p. 100] - analogue 1. Hexagonal honeycombs are the most technologically advanced and demanded type of adhesive honeycomb fillers, but when laid out on curved surfaces, they exhibit a saddle effect (see Fig. 1a).

This method has disadvantages, namely:

a) the inability to lay out honeycomb panels on surfaces of complex curvature;

b) low local interlayer strength at the places of gluing sheets in a honeycomb package.

A patent is known for a method of manufacturing a flexible honeycomb core in which the so-called “Jackson star” acts as a unit cell (see FIG. 1b). The cells of this structure are identical and have a cross section consisting of three identical segments located at the same angle to the common axis. The cross section of each cell has four adjoining sides of a regular hexagonal configuration so that the intersections between the segments are non-linear and give flexibility to the structure. However, the manufacture of this type of honeycomb blocks by the method of stretching the package in practice is not feasible and is carried out, as a rule, by the profiling method [US Patent No. 3,991245, MKI B32B 3/12. Flexible honeycomb structure / W.T. Jackson Publ. November 9, 1976] - analogue 2.

This method has disadvantages, namely:

a) the difficulty of combining profiled surfaces on which adhesive strips are applied;

b) the limitations of the materials used: the use, for example, only glass and knit fabrics previously impregnated with binders;

c) the impossibility of manufacturing large-sized cellular blocks;

d) the impossibility of obtaining glass cells with cell faces less than 6 mm due to the destruction of glass fibers in the process of pressing corrugations.

As a prototype, the patent of the Russian Federation No. 2272712, IPC B32B 3/12 was selected. A method of manufacturing a honeycomb / B.C. Volkov, V.A. Razumovsky, A.M. Kryukov, N.A. Sadikova. Publ. 03/27/2006, the Method includes the following operations: applying adhesive strips to the fiberglass cloth in the longitudinal direction, cutting in the direction perpendicular to the adhesive strips, fiberglass cloths on the blanks, assembling the honeycomb package by laying with the offset of each blank half the pitch of the adhesive strips relative to the previous one, bonding the blanks of the honeycomb package according to a given mode and thermal stabilization of a freely suspended honeycomb package, obtaining a honeycomb block with a given cell face by stretching the honeycomb, prop itka cell block polymer binder, followed by thermosetting it. The honeycomb block obtained after thermosetting is cut into honeycomb panels of the required thickness.

This method has a significant drawback: the inability to lay out honeycomb panels on surfaces of complex curvature.

The objective of the invention is the development of a method of manufacturing a honeycomb core based on fiberglass, providing the possibility of its use in the manufacture of products of complex curvature.

The proposed method includes applying adhesive strips to the fiberglass cloth in the longitudinal direction, cutting the fiberglass cloth onto the blanks in the direction perpendicular to the adhesive strips, assembling the honeycomb by stacking the blanks with each blank offset from the previous half step of the adhesive strips, bonding the blanks of the honeycomb according to a given mode , thermal stabilization of a freely suspended cellular packet, formation of a cellular block with a given cell face by stretching the cellular packet, impregnated the honeycomb block with a polymer binder followed by thermosetting and cutting the honeycomb block into honeycomb panels of a given height, characterized in that in the cell panels along their entire area, the faces of three adjacent cells in contact are uniformly removed to the height of the honeycomb panel, with the part being removed cell faces is 0.25-0.33 of the length of the face (see Fig. 2A). When laying on spherical surfaces due to the uniform removal of part of the faces of three adjacent cells (nodal connections) in the honeycomb panel, the flexibility of the honeycomb core is achieved. With an increase in the value of the removed part of the length of the cell face, the remaining part of the face glued from two layers of fiberglass will delaminate, and with a decrease, the required flexibility of the honeycomb core will not be achieved.

Uniform removal of nodal connections of three hexagonal elementary cells (see Fig. 2b) forms a convex-concave unit cell, called by the authors of this invention “reinforced by the Jackson star”. In this case, the reinforcements are formed by the remains of the faces that made up the nodal connection of the three elementary hexagonal cells. Patented honeycomb core is easily laid out on a spherical surface (see Fig. 3).

The patented method is most relevant for adhesive hexagonal honeycombs (cell edge length 4.2-12 mm) used in the form of honeycomb panels in the range of heights from 3 to 23 mm. The correct geometry of their cells is provided by the design of the snap-in [RF Patent No. 2393094, MKI B32B 3/12. Frame for fixing and impregnating a stretched honeycomb bag / B.C. Volkov, V.A. Razumovsky, A.M. Kryukov, A.B. Mukhamedzhanov. Publ. 06/27/2010].

It is the correct geometry of the cells that involves the use of automated methods for removing nodal joints, for example, die cutting equipment, a coordinate milling machine with CNC, laser cutting and other known methods.

Example 1. A honeycomb core was prepared with a side size of 8 mm hexagonal cells. For this purpose, stripes of phenol-polyvinyl acetal adhesive BF-2, GOST 12172-74 (curing temperature 150 ° C), with a viscosity of 48 s, were applied in the longitudinal direction to the T-10 fiberglass fabric, based on fibers from aluminosilicate silicate-free glass, GOST 19170-2001, in the longitudinal direction using a VZ-246 viscometer using a ribbed shaft with a spacing of 32 mm ribs and dried them in a vertical shaft of an applicator at temperatures in the zones of 45, 65 and 75 ° C. The canvas with adhesive strips was cut into blanks with a length of 340 mm and a width of 900 mm, and the honeycomb package was assembled by laying blanks with a displacement of 16 mm. The assembled package of preforms was glued in the press according to the regime: specific pressure 0.28 MPa, heating to a temperature of 80 ° C followed by an exposure of 40 minutes, heating to a temperature of 150 ° C and an exposure of 70 minutes, heating to a temperature of 170 ° C and an exposure of 120 minutes.

The cell package was thermostabilized for 4 hours at a temperature of 170 ° C in a thermostat in a freely suspended state. The honeycomb bag was stretched to cells of a hexagonal shape and fixed in the impregnation frame using rods installed in the cells of the honeycomb bag. After slowly immersing in a binder solution of bakelite varnish LBS-1, GOST 901-78 (a solution of phenol-formaldehyde resin in ethanol) for 21 s using a VZ-246 viscometer, the stretched honeycomb was impregnated for 7 minutes, slowly removed the frame with the obtained honeycomb from the solution and allowed to drain an excess of binder for 15 minutes. The cell block was dried for 3 hours at room temperature, blowing the cells of the cell block with air.

The cell block was heat treated in a thermostat according to the following regime: heating to a temperature of 100 ° C followed by holding for 30 minutes, heating to a temperature of 150 ° C and holding for 90 minutes, heating to a temperature of 170 ° C and holding for 120 minutes. Tensile elements were cut from the obtained honeycomb block and cut into honeycomb panels.

In the honeycomb panel 1 over its entire surface, the nodal connections 2 were evenly removed using a die cutting tool (see Fig. 2a). The length of the removed part of the cell face was 0.25 of the length of the cell face.

Example 2. A honeycomb core was prepared according to Example 1, but based on an electric insulating fabric of the EZ-100 brand, GOST 19907-83. The length of the removed part of the cell face was 0.27 of the length of the cell face.

Example 3. A honeycomb was prepared according to Example 1, but with a hexagonal mesh size of 10 mm. The length of the removed part of the cell face was 0.29 of the length of the cell face.

Example 4. A honeycomb was prepared according to Example 1, but with a hexagonal mesh size of 12 mm. The length of the removed part of the cell face was 0.31 of the length of the cell face.

Example 5. A honeycomb core was prepared according to Example 1, but based on a SP-97K polyimide binder (TP 596.01000.1287) and BC-10T adhesive (GOST 22345-77). We applied strips to the fiberglass fabric of VS-10T glue with a viscosity of 30 s using a VZ-246 viscometer. The assembled package of preforms was glued in a press according to the regime: specific pressure 0.28 MPa, heating to a temperature of 80 ° C followed by holding for 60 minutes, heating to a temperature of 150 ° C and holding for 90 minutes, heating to a temperature of 190 ° C and holding for 120 minutes.

The cell package in the thermostat in a freely suspended state was not thermostabilized. The stretched honeycomb bag was impregnated in a binder solution (SP-97K polyimide binder) with a viscosity of 8 s using a VZ-246 viscometer for 10 min, the frame with the obtained honeycomb block was slowly removed from the solution, and an excess of the binder was drained for 7 min. The cell block was dried for 2 hours at room temperature, blowing the cells of the cell block with air.

Heat treated the cell unit in a thermostat according to the following mode: heating to a temperature of 60 ° C followed by an exposure of 30 minutes, heating to a temperature of 100 ° C and holding for 30 minutes, heating to a temperature of 150 ° C and holding for 30 minutes, heating to a temperature of 170 ° C and 60 min exposure The length of the removed part of the cell face was 0.33 of the length of the cell face.

The relative decrease in density and compressive strength was determined on each honeycomb panel with remote nodal connections.

The results are shown in the table.

The table shows that when removing nodal joints in honeycomb panels, their compressive strength decreases by 15-22% for different brands of honeycombs, however, their residual strength is quite high, which allows these panels to be used for the manufacture of sandwich structures.

At the same time, the compressive strength of SSP-1-10T with sheathing before removal of the nodal joints was 31.2 kgf / cm, and after removal it was 28.0 kgf / cm ² . In this case, the drop in compressive strength SSP-1-10T with skins is 10.2%. That is, the presence of skins in three-layer curvilinear panels reduces the decrease in the strength of fiberglass reinforced plastic with remote nodal joints. In FIG. Figure 1a shows the formation of saddles during one-dimensional bending of the SSP-1-10T panel, while the same panels with remote nodal joints are easily laid out on a spherical surface with a radius of 150 mm (see Fig. 3). That is, the SSP-1-10T panels with remote nodal connections are suitable for laying out on three-dimensional curved surfaces.

Claims (1)

A method of manufacturing a honeycomb core includes applying adhesive strips to the fiberglass cloth in the longitudinal direction, cutting the fiberglass cloth into blanks in a direction perpendicular to the adhesive strips, assembling the honeycomb bag by stacking the blanks with each blank offset from the previous half step of the adhesive strips, gluing the blanks of the honeycomb bag by to a given mode, thermal stabilization of a freely suspended cellular packet, formation of a cellular block with a given cell face by stretching with product package, the honeycomb block is impregnated with a polymer binder, followed by thermal hardening and the honeycomb block is cut into honeycomb panels of a given height, characterized in that the honeycomb panels uniformly remove the faces of three adjacent cells contacting each other to the height of the honeycomb panel, at this removed part of the faces of the cells is 0.25-0.33 of the length of the face.

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